Apple is by far the largest seller of online music in the United States, with 69 percent of the market, according to data from the NPD Group, a marketing consultancy. Amazon’s MP3 store was in second place, with an 8 percent share. Apple is also the largest seller of music, with 26.7 percent of the overall market, up from 12 percent in 2007.

That's right. More than one quarter of all music is sold through Apple. And their practices to keep it this way have started to get the attention of the Feds...